In humans, olfaction, which is one of the body's defense mechanisms, is useful for testing foods and detecting noxious agents in the environment. Interest in the olfactory functions has recently increased. For evaluations of olfactory function, the butanol test and the UPSIT test have been used in western countries, while T & T olfactometry and intravenous tests have been used in Japan. In Korea, normal olfactory detection thresholds by T & T olfactometry have been reported. However, there have been no reports on the butanol test and there are some difficulties, although it is not impossible, in performing identification with T & T olfactometry. We studied the olfactory detection threshold with butanol and identification test on 27 normal persons. The results were as follows : 1) Olfactory detection thresholds were 7.9 on the right side and 8.1 on the left side. 2) There was no difference between smoker and non-smoker in olfactory detection threshold. 3) There was no difference between male and female in olfactory detection threshold. 4) In the identification test, 85.5% of odons were identified accurately, 13.5% were detected but their qualities could not be identified, and 1% was not able to be detected.